Sheet-feeding apparatus

ABSTRACT

An apparatus for feeding individual sheets of paper or the like from the top of a stack upon demand is disclosed. The device includes a &#39;&#39;&#39;&#39;paddle wheel&#39;&#39;&#39;&#39; feeding device which comprises a plurality of flexible blades extending radially outwardly from an axle or hub. The blades are placed in contact with the surface of the upper sheet of a stack and, upon rotation of the hub, sweep the top sheet toward a receiving means. The paddle wheel is caused to rotate by a drive motor whenever a sheet is to be fed. Once the sheet reaches the receiving means, the motor is disengaged. A one-way clutch permits the paddle wheel to be rotated by the sheet as it is withdrawn by the receiving means. The paddle wheel is preferably mounted on a pivoting mechanism to accommodate varying stack heights. Preferably, means are included to remove the paddle wheel from the upper surface of the stack during stack replenishment.

United States Patent [72] Inventor Byung S. Hung San Diego, Calif. [21] Appl. No. 21,827 [22] Filed Mar. 23, 1970 [45] Patented Dec. 28, 1971 [7 3] Assignee Stromberg Datagraphix, Inc.

San Diego, Calili.

[54] SHEET-FEEDING APPARATUS 6 Claims, 7 Drawing Figs.

[52] US. Cl 271/36 [51] Int. Cl B6511 3/02 [50] Field of Search 271/36, 39, 9, 37, 38

[56] References Cited UNITED STATES PATENTS 2,677,542 5/1954 Backhouse et a1 271/53 X 2,204,715 6/l940 Wimmer 271/36 2,755,086 7/1956 Lubersky 271/36 3,300,206 l/l967 Cassano et al 271/21 2,080,968 5/1937 Krell ABSTRACT: An apparatus for feeding individual sheets of paper or the like from the top of a stack upon demand is disclosed. The device includes a paddle wheel" feeding device which comprises a plurality of flexible blades extending radially outwardly from an axle or hub. The blades are placed in contact with the surface of the upper sheet of a stack and, upon rotation of the hub, sweep the top sheet toward a receiving means. The paddle wheel is caused to rotate by a drive motor whenever a sheet is to be fed. Once the sheet reaches the receiving means, the motor is disengaged. A one-way clutch permits the paddle wheel to be rotated by the sheet as it is withdrawn by the receiving means. The paddle wheel is preferably mounted on a pivoting mechanism to accommodate varying stack heights. Preferably, means are included to remove the paddle wheel from the upper surface of the stack during stack replenishment.

PATENTEnniczaisn SHEET 1 OF 3 FIG. 1

INVENTOR.

BYUNG S. HONG ATTORNEY PATENTED M82819?! SHEET 2 UF 3 INVENTOR.

BYUNG S. HONG ATTOR NEY SHEET-FEEDING APPARATUS BACKGROUND OF THE INVENTION Sheet feed means have come into wide use in conjunction with office copiers, data processing equipment, printing equipment, etc. While a great many sheet feeding mechanisms have been developed, further improvements are necessary for optimum operation with modern, high-speed sheet processing equipment.

Many of the prior sheet-feeding mechanisms occasionally malfunction, feeding more than one sheet at a time or failing to feed on demand. Consistent feeding is often difficult to achieve with different stack heights. Complex elevator devices are often required to maintain the top of the stack at a uniform height.

Many sheet feeders use a roller in substantially line contact with the upper surface of the stack. However, problems occur where coated sheets are fed, since the top sheet being fed abrades the second, stationary sheet along the line of roller pressure. This abrasion may adversely affect the sheets, both in appearance and function. The pressure of the roller may also indent or crease the sheets along the line of contact, increasing the chance of jamming the device during feeding.

In addition, roller-type feed means often have a short, useful life span. Depending upon the type of sheets fed, the roller may either develop a glazed surface or may wear rapidly and develop flat spots. Any of these conditions is likely to interfere with the ability of the roller to positively feed sheets.

Any slippage between the feed roller and sheets is likely to cause objectionable abrasion or pressure marks on the sheets or wear to the roller.

With the recent development of high-speed copiers and duplicators using zinc-oxide coated sheets in electrostatic processes the problems of abrasion and pressure marks discussed above have become more critical, since the zincoxide coatings are relatively rough and abrasive. In such systems, the appearance of copies may be degraded due to visible physical damage to the coating and the copying qualities of the coating may be impaired by abrasion. In addition, the feed roller is subject to rapid wear where slippage between roller and the abrasive sheet surface occurs. In the event of a jammed sheet, the continued rotation of the feed roller will damage the top sheet.

Thus, there is a continuing need for improved sheet-feeding apparatus, especially for use in electrostatic copying equipment.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide a sheet feeding apparatus overcoming the above-noted problems.

Another object of this invention is to provide a sheet-feeding apparatus which substantially eliminates abrasion and pressure damage to the fed sheets and feeding device.

Another object is to provide a sheet-feeding apparatus which is automatically moved out of contact with the sheet stack during stack replenishment.

Still another object is to provide a simple, economical sheet feeding apparatus capable of operating with widely varying sheet stack heights.

A further object is to provide a sheet-feeding apparatus which does not apply localized high pressure to the sheet stack.

The above objects, and others, are accomplished in accordance with this invention by a sheet feeding apparatus using a paddle wheel feeding device to sweep single sheets from the top of a stack to a sheet receiving means, which conveys the individual sheets to further operating stations, e.g., for printing, copying, etc. The paddle wheel comprises a rotatable hub to which a plurality of radially extending flexible elastomeric paddles or blades are fixed. As the paddle wheel rotates, the blades bend as they contact the top sheet of a stack, giving a relatively large contact area between blades and sheet. The top sheet is moved by a sweeping" action into the nip between receiving rollers or any other suitable receiving means. This eliminates the heavy localized pressure required with conventional feed rollers, substantially eliminating abrasion damage to the stationary second sheet when the top sheet is moved. If the top sheet should jam the blades will slip on the sheet. Little abrasion damage occurs to either the blades or the top sheet, because of the low pressure therebetween.

Preferably, the rotatable paddle wheel is mounted on a pivoted arm or bracket as described below, so as to easily ac commodate widely varying stack heights.

It is also preferred that the paddle wheel be driven only long enough to bring the leading edge of the sheet being fed into positive contact with the sheet receiving means, such as the nip between receiving rollers. A one-way clutch between the paddle wheel and the drive motor allows the paddle wheel to be rotated by the sheet as it is completely withdrawn from the stack. This prevents abrasion damage which might occur if substantial slippage were permitted between blades and sheet, since it may be desirable to deliver the sheet to the receiving roller nip at a higher or lower speed than the sheet is to be moved by the receiving rollers.

Means for moving the paddle wheel out of contact with the sheet stack during replenishment of the stack may also be ineluded. Preferably, the disengaging means automatically lifts the paddle wheel out of contact when the stack support means is reinserted after replenishment. This prevents the paddle wheel from dragging against the top sheet during reinsertion of the stack support into the apparatus, which would move the top sheet out of the desired position for feeding. When the stack support is completely reinserted, the preferred disengaging device will return the paddle wheel into contact with the stack without appreciably disturbing the position of the top sheet.

BRIEF DESCRIPTION OF THE DRAWINGS Details of a preferred embodiment and various features of the invention will become apparent upon reference to the drawings, wherein:

FIG. I is a perspective view of the overall sheet supply system of this invention;

FIG. 2 is a plan view of the paper feed mechanism;

FIG. 3 is an elevation view of the feed mechanism shown i FIG. 2;

FIG. 4 is a view in elevation of one end of the paddle wheel member;

FIG. 5 is a plan view, partially in section, of the paddle wheel member;

FIG. 6 is a view in elevation of one end of an alternative embodiment of the paddle wheel member; and

FIG. 7 is a plan view, partially in section, of the one-way drive clutch.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. I, there is seen a drawer assembly 10 on which is mounted a paper tray 12 and above which is suspended a feed mechanism generally designated [3. Drawer I0 is mounted on slides 15 which are secured to the inner walls of an apparatus (not shown) to which paper from stack 17 is to be fed. In a conventional manner, slides l5 permit drawer 10 to be drawn out of the overall apparatus by means of handle 19 on front panel 20. Slides 15 are secured to drawer side panels 22 and 23, which are fastened to front panel 20 and support paper tray 12 As shown in FIG. 1, paper stack 17 is supported on tray 12 and maintained in position by upstanding slide members 24, 25, 26 and 27 and back member 28. A pair of pressure pads 32 and 33, pivotably mounted on side members 24 and 25, are preferably provided to help prevent more than one sheet of paper from stack 17 being fed at a time. A soft elastomeric layer 35 is provided between pressure pads 32 and 33 and paper stack 17. This layer 35 is urged into pressing contact with paper stack 17 by any suitable means, such as springs within hinges 37 or latches holding pressure pads 32 and 33 in the position shown in FIG. I. These elastomeric layers exert a constant frictional force on the edges of the sheets in stack 17. While the frictional force exerted by the feed device on top sheet 39 is sufiicient to overcome the edge friction when feeding the top sheet, the friction of the top sheet moving against the second sheet is not. Thus, the second sheet is held in position on stack 17 while the top sheet is being fed.

The leading edge of tray 12 includes a guide finger means 40 which guides top sheet 39 into a sheet receiving means (not shown). When the leading edge of sheet 39 reaches the receiving means, which may typically be the nip between contiguous rotating rollers, the sheet is then pulled by the receiving means. As is further discussed below, once the feed device has brought the leading edge of sheet 39 into the receiving means, the feed means drive stops and the feed means is rotated only by friction between it and the sheet being withdrawn by the receiving means.

As seen in FIG. 1-3, the feed mechanism 13 is supported by a shaft 45 which is rotatably supported by bearings (not shown) secured to the overall apparatus frame. A drive motor 46 is provided to rotate shaft 45 through a one-way clutch 47 (shown in detail in FIG. 7). A generally U-shaped bracket 49 is mounted in bearings on shaft 45. Bracket 49 is maintained in the desired position along shaft 45 by retaining rings 51, 52 which engage grooves in shaft 45. A paddle wheel drive member 54 is joumaled for rotation in bearings in the extended legs of bracket 49. Retaining rings 56, 57 riding in grooves in paddle wheel support shaft 59 maintain paddle wheel 54 in position with respect to bracket 45 Paddle wheel 54 is driven by means of a drive belt 60 extending to shaft 45 by set screw 62 and driven pulley 63 secured to a shaft 59 by set screw 64. Thus, when drive motor 46 rotates shaft 45 paddle wheel 54 will be rotated.

Since bracket 49 is loosely supported by shaft 45, gravity will urge paddle wheel 54 into contact with the paper stack 17 as seen in FIG. 1. When paddle wheel 54 is rotated, the paddles or blades 66 will sweep top sheet 39 off of stack 17. These blades 66 are made of an elastomeric material having high surface friction characteristics, such as gum rubber. The blades 66 bend as shown in FIG. 1, giving a large contact area with top sheet 39.

When drawer is pulled out for replenishment of paper stack 17, bracket 49 will pivot about shaft 45 under the infiuence of gravity until paddle wheel 54 hangs below shaft 45. It would be undesirable for drawer 10 to be pushed back into place with blades 66 of paddle wheel 54 in contact with paper stack 17, since as paddle wheel 54 was swung back into position shown in FIG. 1, the top sheet would be displaced by friction against blades 66. Therefore, it is preferred that a means be provided to lift paddle wheel 54 out of engagement with stack 17 during the reinsertion of drawer 10.

An L-shaped bracket 70 is rotatably mounted on shaft 45 and held in place by retaining rings 52 and 71. A pin 72 secured to bracket 70 extends under one leg of bracket 49. The extended leg 74 and pin 72 are arranged so that when leg 74 is moved into an approximately horizontal position, pin 72 engages bracket 49 and lifts paddle wheel 54 out of contact with paper stack 17. A cam bar 76 is secured to drawer 10. As drawer 10 is withdrawn for replenishment of paper stack 17 or service, bracket 49 swings down to a position hanging below shaft 45. Then, when drawer 10 is reinserted, leg 74 engages end 78 of cam bar 76 and rides along the surface of bar 76. As leg 74 approaches a horizontal position, pin 72 moves up under bracket 49, lifting paddle wheel 54. Once drawer 10 is substantially fully inserted, leg 74 reaches the downwardly sloping portion 79 of cam bar 76. As leg 74 returns to a vertical position, pin 72 moves down out of engagement with bracket 49, allowing paddle wheel 54 to drop into contact with paper stack 17. The unit is then ready to begin feeding individual sheets.

Details of the paddle wheel 54 are shown in FIGS. 4 and 5. In this preferred embodiment, blades 66 are approximately rectangular in shape, with an enlarged bead 83 along one edge which fits in a corresponding recess or slot in hub 85. Blades 66 may comprise any suitable material. Preferably, blades 66 should be flexible and have high friction surfaces. Gum rubber has been found to be an especially effective material. Any suitable number of blades may be used. An arrangement as shown, using six blades, is preferred, since this number gives optimum paper surface contact area and a highly effective sweeping action. While the blades may be made by any suitable process, extrusion through an orifice having the shape of the blade cross section, as seen in FIG. 4, is especially effective and economical. Hub 85 may comprise any suitable material, such as aluminum. The recesses or slots for beads 83 may be formed by a casting or extrusion operation, by a drilling and/or milling operation, or any other suitable process. As seen in FIG. 5, shaft 59 is preferably made up of a pair of stub shafts secured in holes in the ends of hub 85. Alternatively, a single shaft 59 passing entirely through hub 85 could be used. A flat portion 86 is provided adjacent one end of shaft 59 for engagement with the driven pulley set screw 64.

An end view of an alternative embodiment of paddle wheel 54 is shown in FIG. 6. Here, hub 185 mounted on shaft 159 has a plurality of outwardly extending slotted portions each having a generally U-shaped cross section. The inner edges of rectangular blades 166 are placed in these slots. The blades may be held in place with an adhesive, and/or by inwardly deforming the slotted portions to compress the inner edges of blades 166.

A suitable one-way clutch 47 for connecting drive motor 46 to shaft 45 is shown, partially in section, in FIG, 7. Clutch 47 includes a generally cylindrical housing 90 having a cylindrical base 91 at one end adapted to fit over the output shaft or motor 46. At least one set screw 92 is provided to lock housing 90 to the motor shaft. A conventional roller clutch assembly 94 (of the one-way roller bearing type available from the Bearing Division of the Torrington Company) is located within a bore 95 in the other end of housing 90. Clutch assembly 94 is sized to fit over the end of shaft 45.

In operation, when a sheet of paper is required by the apparatus with which this paper feed assembly is used, motor 46 is activated only long enough for paddle wheel 54 to sweep top sheet 39 into operative contact with the paper receiving means (not shown). The, motor 46 is deenergized. As top sheet 39 is withdrawn by the receiving means, friction between top sheet 39 and paddle wheel 54 will continue to rotate the paddle wheel and shaft 45. One-way clutch 47 permits this continued rotation of shaft 45 without forcing the motor output shaft to rotate.

While various components and proportions have been described in the above description of preferred embodiments, various alternatives may be used, where suitable as indicated above, with similar results.

Other variations and modifications of the apparatus of this invention will occur to those skilled in the art upon reading this disclosure. These are intended to be included within the scope of this invention, as defined in the appended claims.

Iclaim:

l. A sheet feed member comprising a rotatable generally cylindrical hub having a plurality of spaced grooves in the surface thereof, said grooves extending substantially parallel to the centerline of said hub; and a plurality of generally rectangular elastomeric blades each secured in one of said grooves and extending radially outwardly therefrom, each blade lying in a plane which includes said hub centerline, said blades having a high surface friction characteristics and being capable of bending under the force of gravity when said feed member is supported on a planar surface, whereby substantially uniform contact is maintained between a substantial portion of the faces of said blades and said surface upon rotation of said hub.

2. The sheet feed member according to claim 1 wherein six blades are secured in six equally spaced grooves in said hub.

3. The sheet feed member according to claim 2 wherein said blades comprise gum rubber.

4. The sheet feed member according to claim 3 wherein said grooves have a generally cross section connected to the surface of the hub by an intervening slot and said blades each have an enlarged bead along one edge having a cross-section substantially equal to that of said grooves, whereby said blades are held in said grooves by the interlocking relationship between blades and grooves.

5. A sheet feed apparatus comprising:

a. support means for holding a stack of sheets;

b. sheet guide means at a first end of said stack;

c. a rotatable first shaft supported in a fixed position above said support means;

d. a bracket pivotable mounted on said first shaft, adapted to extend approximately parallel to said sheets away from said first end thereof;

e. a paddle wheel mounted on a second shaft rotatably supported by said bracket, said paddle wheel comprising a rotatable hub secured to said second shaft and having a plurality of spaced generally rectangular blades extending radially outwardly from said hub, each blade lying generally in a plane which includes said second shaft and adapted to bend and conform to a sheet surface when brought into contact therewith;

f. drive means operatively connected to rotate said first shaft;

g. drive linkage means operatively connected between said first and second shafts to rotate said paddle wheel; whereby rotation of said first shaft causes said paddle wheel to sweep the top sheet from said shaft toward said first shaft and said guide means.

6. Apparatus according to claim 5 further including separation means permitting replenishment of said stack without interference from said paddle wheel which comprises: 

1. A sheet feed member comprising a rotatable generally cylindrical hub having a plurality of spaced grooves in the surface thereof, said grooves extending substantially parallel to the centerline of said hub; and a plurality of generally rectangular elastomeric blades each secured in one of said grooves and extending radially outwardly therefrom, each blade lying in a plane which includes said hub centerline, said blades having a high surface friction characteristics and being capable of bending under the force of gravity when said feed member is supported on a planar surface, whereby substantially uniform contact is maintained between a substantial portion of the faces of said blades and said surface upon rotation of said hub.
 2. The sheet feed member according to claim 1 wherein six blades are secured in six equally spaced grooves in said hub.
 3. The sheet feed member according to claim 2 wherein said blades comprise gum rubber.
 4. The sheet feed member according to claim 3 wherein said grooves have a generally cross section connected to the surface of the hub by an intervening slot and said blades each have an enlarged bead along one edge having a cross section substantially equal to that of said grooves, whereby said blades are held in said grooves by the interlocking relationship between blades and grooves.
 5. A sheet feed apparatus comprising: a. support means for holding a stack of sheets; b. sheet guide means at a first end of said stack; c. a rotatable first shaft supported in a fixed position above said support means; d. a bracket pivotable mounted on said first shaft, adapted to extend approximately parallel to said sheets away from said first end thereof; e. a paddle wheel mounted on a second shaft rotatably supported by said bracket, said paddle wheel comprising a rotatable hub secured to said second shaft and having a plurality of spaced generally rectangular blades extending radially outwardly from said hub, each blade lying generally in a plane which includes said second shaft and adapted to bend and conform to a sheet surface when brought into contact therewith; f. drive means operatively connected to rotate said first shaft; g. drive linkage means operatively connected between said first and second shafts to rotate said paddle wheel; whereby rotation of said first shaft causes said paddle wheel to sweep the top sheet from said shaft toward said first shaft and said guide means.
 6. Apparatus according to claim 5 further including separation means permitting replenishment of said stack without interference from said paddle wheel which comprises: a. means permitting movement of said stack support means in a direction generally toward said first end of said stack; b. said bracket means adapted to be rotated by gravitational forces so that said paddle wheel hangs generally vertically downwardly from said first shaft with said stack support removed; and c. cam follower means connected to said first shaft adapted to ride on a cam surface during replacement of said stack support means, to lift said paddle wheel above said sheet stack during said replacement. 